Swedes Daniel Chopra and Jesper Parnevik led the early European challenge in the first round of the Pods Championship at Palm Harbour in Florida.
Chopra carded a four-under-par 67 to move into second with his compatriot and former Ryder Cup star a further stroke behind.
However, both trailed unheralded Cliff Kresge, who made a sizzling start on his way to claiming the clubhouse lead with a six-under-par 65 on the demanding Innisbrook course.
"For 11 holes it was a dream round," he said. "My irons were sharp and I was driving the ball well."
An eagle at the par-five 11th took Kresge to eight-under but he dropped a couple of shots coming home to finish his day only two strokes clear of Chopra with half the field still on the course.
"I'd much rather be eight under than six under but six under's a hell of a score," added Kresge, whose round was highlighted by an eagle at the par-four sixth where he holed a six-iron from 184 yards.
His eagle at the 11th was slightly more regulation, sinking a 10-foot putt having reached the green in two.
Kresge, 38, has never finished better than third in a PGA Tour event. He has, however, enjoyed a solid start to the season, making the cut in all six starts.
South African Trevor Immelman is four off the lead after a two-under 69, a score matched by former Ryder Cup captain Tom Lehman and one of the members of his defeated team last September Chris DiMarco.
Sergio Garcia, one of Europe's stars at the K Club last year, shot a 70 while Brian Davis carded a one-over 72.
